This invention relates generally to quartz analog electronic timepieces and more particularly to movements for three and two hand timepieces.
Watch manufacturers of quartz analog watches offer three hand timepieces with a sweep second hand, as well as two hand timepieces without a second hand, often used in smaller fashion watches. If a watch manufacturer can use fewer components or piece parts in a timepiece movement, and if a number of these components or pieceparts are common to a number of different types of movements, the savings which can be achieved are significant. This is because the common parts can be manufactured in larger quantities, leading to lower cost. Movements of assemblies can be manufactured in advance suitable for conversion to selected types of movements by adding components which are special only to a particular movement.
One of the problems facing the watch designer who is attempting to design several movements using common elements is that the space for the gear train elements and the choices for arranging the gear train are very limited. Therefore, any alteration of a component often affects other components as well.
Three hand movements for quartz analog timepieces are well known in the art, wherein a stepping motor is pulsed Periodically by an integrated circuit to rotate the stepping motor rotor 180 degrees. The rotor rotation is used to step a sweep second hand once every second, so that it rotates once per minute. The reduction may be accomplished through a gear train by driving a seconds wheel assembly through an intermediate wheel reduction gear. The seconds wheel has a pinion driving a third wheel assembly which drives a center wheel to which the minute hand is attached. The center wheel, through a minute wheel assembly, drives an hour wheel to which an hour hand is attached. Such a movement is seen in my U.S. Pat. No. 4,744,066 issued May 10, 1988, and assigned to the present assignee.
Movements are also well known in the art in which a two hand movement utilizes an integrated circuit supplying pulses at a substantially slower rate, e.g. once per minute to a stepping motor rotor. The stepping motor rotor pinion may drive the center wheel directly, or through a reduction gear sometimes known as an intermediate wheel assembly. Thereafter, the movement gear train is the same as described above. A two-hand movement with rotor driving the center wheel directly is seen in U.S. Pat. No. 4,647,218 issued Mar. 3, 1987, to Paul Wuthrich and assigned to the present assignee.
The prior art movements above require one movement for a three hand timepiece and require a completely different movement for a two hand timepiece. It would be desirable to provide a movement subassembly of common elements, to which special parts or components could be added to provide either a two hand or a three hand timepiece, as desired.
Accordingly, one object of the present invention is to provide a movement subassembly suitable for adapting to a movement for either a three or a two hand timepiece, said subassembly using piece parts common to both movements.
Another object of the invention is to provide for an improved three hand timepiece which is convertible to a two hand timepiece.
Another object of the invention is to provide an improved two hand timepiece which is convertible to a three hand timepiece.
Yet another object of the invention is to provide an improved movement subassembly which maximizes the number of common components for in two hand and three hand timepiece movements, and minimizes the number of special components.